Interstitial lung diseases, now known as diffuse proliferative lung diseases, are a spectrum of diffuse parenchymal lung disease that is characterized by variable degrees of pulmonary fibrosis3. Pulmonary fibrosis is a component of various interstitial pneumonias3. These disorders are characterized by varying degrees of inflammation, aberrant fibroblast proliferation, and extracellular matrix deposition that result in distortion of pulmonary architecture that compromises pulmonary function3, 4. There are many causes of pulmonary fibrosis including exposure to fibrosis-inducing agents such as silica5, coal dust6, radiation7 and certain chemotherapeutic agents7. Despite its prevalence, the pathogenesis of pulmonary fibrosis is not completely understood and treatment options for the resolution of pulmonary fibrosis are lacking.
Approximately 35% of interstitial lung diseases can be grouped into a condition known as idiopathic pulmonary fibrosis (IPF)12. A comprehensive epidemiological study investigating the incidence of IPF, revealed a general prevalence rate of approximately 20 cases per 100,00012. This incidence was higher in individuals over 75 years of age where 175 cases per 100,000 were noted. A more recent study demonstrated a prevalence of approximately 43 cases per 100,000 and an incidence of 16.3 cases per 100,000 patient years.13 These data suggest that the incidence and prevalence of IPF in on the rise. IPF is a chronic and particularly devastating form of interstitial lung disease. It is largely untreatable and leads to death within 3 to 8 years of diagnosis14. There are no effective disease-modifying treatments for IPF.